I thought Gina was just a hologram. As far as Colette goes, who was was she in the first place? I have no memory of her ever appearing in Half-Life, Opposing Force or Blue-Shift, much less the demo Uplink.

Valve hasn't mentioned them. Nor have they mentioned Rosenburg or all the other escaped Black Mesa Personnel. Now that I think about it though, there is an Opposing Force 2 mod being developed, why does nobody do Decay 2?

Marc Laidlaw does not take the expansions into thought when wrting for Half-Life, so Collette does does not exist nor Rosenburd, Shepard and so on. Gina is canon to the orignal Half-Life but kind of just dissapeared after HL1. Your welcome.